Preparation of inorganic oxide monofilaments



United States Patent 3,270,109 PREPARATION OF INORGANIC OXIDE MONOFILAMENTS Robert H. Kelsey, Chagrin Falls, Ohio, assignor to Horizons Incorporated, Cleveland, Ohio, a corporation of New Jersey No Drawing. Filed Mar. 15, 1963, Ser. No. 265,361

4 Claims. (Cl. 264-178) This invention relates to inorganic oxides in monofilament form and to the preparation of such filaments by a Wet spinning process.

In my United States patent application Serial No. 252,083, filed January 17, 1963, I have described the preparation of oxide monofilaments by a dry spinning process utilizing compositions of the type described in United States patent application Serial No. 72,277, filed November 29, 1960, which issued as United States Patent 3,180,741 on April 27, 1965, and which corresponds to French Patent 1,316,535.

In dry spinning processes in which a filament of suitable composition is extruded into air or other gaseous atmospheres the properties of the extruded filaments may be adversely affected unless the temperature and relative humidity of the air or other gas into which the filament is spun are suitable. Low temperature and/or high rela tive humidity tend to inhibit the escape of volatile constituents from the filament, and thus slow its solidification. Furthermore, spinning into air or gaseous atmosphere does not readily permit the addition of modifying constituents into the freshly spun filament since only a limited number of such constituents may be placed in the Vapor phase.

The procedure described in my above noted patent application requires that the temperature of the liquid composition being extruded and the temperature of the extrusion device be controlled within narrow limits in order to produce strong filaments suitable for further processing.

In an effort to avoid limitations characteristic of dry spinning, wet spinning i.e. extrusion of monofilament forming compositions into liquid was explored. Spinning the filament into a liquid, wet spinning, allows precise control of the environment into which the filament is extruded. With a liquid bath of suitable composition, solidification of the filament may be accomplished by controlled diifusion of its volatile constituents into the surrounding liquid, by chemical reaction between the constituents of the fiber and those of the bath, or both.

It was found that aqueous liquids were wholly unsuitable and that organic liquids immiscible with water did not wet the face of the spinnerette, but rather trapped the emerging fiber and its liquid constituents, preventing-any development of any useful filaments.

The principal object of the present invention is to provide a process wherein compositions of the type indicated are spun into a readily controlled environment so constituted as to cause them to form solid filaments which may be processed into strong products by heating the extruded filament in the manner disclosed in the above noted patent.

Another object of the present invention is to provide a procedure whereby relatively small amounts of additives may be incorporated into the monofilaments for the purpose of influencing the properties of the final product.

These and other objects are accomplished by extruding the filament forming composition into a liquid consisting of tertiary butyl alcohol or of tertiary butyl alcohol plus up to about 15% by weight of one or more additives intended to be incorporated into the freshly formed monofilament during its residence in the coagulating bath.

As indicated in the tabulated results simple alcohols such as methyl alcohol and ethyl alcohol act in the same manner as water and effectively dissolve or depolymerize the monofilament forming composition when efforts were made to utilize them as the coagulant bath. It was further found that hydrocarbon such as benzene or toluene or other liquids which are not soluble with water trapped a droplet of the aqueous spinning solution on the face of the spinnerette and effectively prevented formation of the filament. Consequently it will be evident that the liquid into which the filament is extruded is critical in the processing of inorganic oxide spinning solutions of the type indicated.

The invention will 'be better understood by reference to the following specific example of a preferred mode of practicing the same.

A solution of zirconium acetate in water containing the equivalent of 11% zirconium oxide by weight and having an initial viscosity of between 2 and 4 centipoises was vacuum concentrated at 25 C. for 36 hours after which it exhibited an equivalent of a zirconium oxide concentration of 82% on a weight basis. The vacuum concentrated product was clear somewhat viscous liquid having a viscosity of about 8500 centipoises. Upon being permitted to stand at 25 C. for about 1 week the viscosity of the liquid was found to have risen to about 20,000 centipoises and this could be increased by heating at up to C. for short intervals of time.

In the wet spinning process, compositions with viscosities of at least about 50,000 centipoises, e.g. 52,500 centipoises were extruded through orifices, 0.003, 0.005 and 0.010 inch in diameter and having an orifice length equal to the diameter, under pressures ranging from 50* to 400 psi.

TABLE I Effect of spinning bath composition on monofilament Bath Density Solubility Result (g./em. in water Methyl alcohol Dissolved fiber. Ethyl alcohol. D

0. n-Propyl alcohol Some short filament.

ooooooo ooqoooooqq HQOHWOQDw monobutyl ether.

These tests were made with 52,500 centipoise zirconium prototype solution. In some cases as much as 50 feet of 10 strand roving were prepared by the use of the intermediate alcohols (e.g. t-butyl) in the spinning bath. Fibers stabilized in this way were remarkably flexible; a roving could be hung over a fii-inch rod without evident damage. The fibers must be handled with extreme care however because their green strength is low.

While not wishing to be bound by any specific theoretical explanation it appears possible that with propyl and butyl alcohols some esterification may have taken place. In any event the monofilament spun into t-butyl alcohol was observed to exhibit much less solubility in water than similar filament spun into air.

In addition of the advantages cited above, the wet spinning method described provides a contsant environment for the emergent fiber, independent of atmospheric conditions; the bath may be varied with respect to the temperature and composition at will. Wet spinning avoids to a large extent the effect of gravity on the fiber, and movement of filaments may be precisely controlled. Since there are no random variations in the movement of the fluid making up the bath, it is not necessary to shield the 3 filament nor to provide special heating for it as it is drawn.

The method described above is applicable not only to the spinning of zirconia monofilaments but also to the production of alumina, and other oxides of the type described in said French patent, namely the oxides of aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, yttrium, zirconum, the lanthanide rare earths, hafnium, and thorium. These are initially prepared as dilute aqueous solutions of water soluble organic salts of the metals and later concentrated and polymerized to produce a spin bath.

Having now described the invention in accordance with the patent statutes I claim:

1. In a process for preparing inorganic oxide filaments which comprises preparing a dilute aqueous solution of an oxygen containing organic salt of a metal selected from the group consisting of aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, yttrium Zirconium, the lanthanide rare earths, and hafnium; concentrating said solution to a viscosity of at least about 50,000 centipoises and then forming said viscous liquid into filaments, and thereafter heating said filaments to a temperature sufiicient to convert the same to said metal oxide, the improvement which comprises extruding said liquid through an orifice and directly into a liquid comprising an alcohol selected from the group consisting of straight chain and branched chain aliphatic alcohols with not less than 3 and not more than 6 carbon atoms.

2. The process of claim 1 wherein the inorganic oxide is zirconia, the prepared solution is a solution of zirconium acetate and the alcohol is tertiary butyl alcohol.

3. The process of claim 1 wherein the inorganic oxide is alumina, the prepared solution is a solution of aluminum acetate and the alcohol is tertiary butyl alcohol.

4. The process of claim 1 wherein the orifice diameter does not exceed 0.010 inch.

References Cited by the Examiner UNITED STATES PATENTS 2,338,463 1/1944 Skaupy et al. 264l83 3,180,741 4/1965 Wainer et al 23-l40 XR FOREIGN PATENTS 352,681 7/1931 Great Britain.

OSCAR R. VERTIZ, Primary Examiner.

H. T. CARTER, Assistant Examiner. 

1. IN A PROCESS FOR PREPARING INORGANIC OXIDE FILAMENTS WHICH COMPRISES PREPARING A DILUTE AQUEOUS SOLUTION OF AN OXYGEN CONTAINING ORGANIC SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, TITANIUM, VANADIUM, CHROMIUM, MANGANESE, IRON, COBALT, NICKEL, YTRIUM ZIRCONIUM, THE LANTHANIDE RARE EARTHS, AND HAFNIUM; CONCENTRATING SAID SOLUTION TO A VISCOSITY OF AT LEAST ABOUT 50,000 CENTIPOISES AND THEN FORMING SAID VISCOUS LIQUID INTO FILAMENTS, AND THEREAFTER HEATING SAID FILAMENTS TO A TEMPRATURE SUFFICIENT TO CONVERT THE SAME TO SAID METAL OXIDE, THE IMPROVEMENT WHICH COMPRISES EXTRUDING SAID LIQUID THROUGH AN ORIFICE AND DIRECTLY INTO A LIQUID COMPRISING AN ALCOHOL SELECTED FROM THE GROUP CONSISTING OF STRAIGHT CHAIN AND BRANCHED CHAIN ALIPHATIC ALCOHOLS WITH NOT LESS THAN 3 AND NOT MORE THAN 6 CARBON ATOMS. 